When, instead of a brain, a person has a third lung in the space where their brain should be. Unfortunatley, this means they have a bigger air capacity, allowing them to talk more, but because they have no brain, they don't have the ability to think through about what they're going to say first.

A common name for somebody with TLS is airhead. Which is ironic because lungs of course breathe in air.

TLS stands for talking loud syndrome. if someone talks really loud all the time (or usually ) they have TLS. it is not TALKS loud syndrome. it is TALKING loud syndrome. TLS can be a side effect of headphone syndrome

Dean: hey sarah, why does kaie talk so loud?
Sarah: she has TLS.
Katie: YEAH! I HAVE TLS!!!! A LOT!!!